We studied the diet composition and diet overlap in sympatric red deer (Cervus elaphus hispanicus) and fallow deer (Dama dama) throughout a whole year in order to determine variation due to season, species, sex and age class by analysing rumen contents samples of 81 red and 69 fallow deer shot monthly during 2008–09 in Sierra de Andújar Natural Park, southern Spain. We assessed diet similarity and possible inter- and intra-specific foraging competition. We found different foraging strategies for both species and sexes during constraint periods, and several theoretical considerations of specific interactions and behaviour are discussed with respect to the Mediterranean environment. In both species an annual diet dominated by grasses was recorded, peaking in spring. Browses were an important food resource at the end of winter and at the end of summer, and fruit more in autumn and winter. Red deer ingested a higher proportion of browse than fallow deer, which consumed more acorns and for a longer time showed a better ability to compensate for nutritional constraint periods. An overall decline in diet similarity in summer and at the end of winter led us to assume that exploitative competition between red and fallow deer and even between sexes was probable. Red deer females showed low diet similarity to other deer, while there was a great diet overlap between red deer males and fallow deer females at the end of summer. Differences detected between both two species and sexes do not always support predictions deriving from specific body size and morpho-physiological characteristics, but can probably be explained as a consequence of different metabolic demands. The relationship between plant nutritional attributes and food selection according to reproductive or physiological status and seasonal demands for both sexes and species should be researched in order to perform a better assessment of deer feeding behaviour.
A workshop was convened in Chile in August 2010 as part of the 7th International Deer Biology Congress (IDBC). Its aim was to explore global differences in the policies and management of overabundant deer in protected areas. The main goal of the workshop was to provide South American researchers and managers with a snapshot of some of the approaches to management of deer overabundance used in a diverse array of case studies from North America, Europe, Australia and New Zealand. Various case studies were presented to illustrate the different methodological approaches in implementing deer control measures. Some general recommendations were formulated.
Evidence based on third-quartile values different from those expected justifies the need for particular reference values taking into account image system and focal distance, as a way to improve patient radiation dose management.
The prevalence of mandibular osteomyelitis, which results in a condition called lumpy jaw, and factors associated with its occurrence were investigated in syntopic free-living populations of red deer (Cervus elaphus hispanicus) and fallow deer (Dama dama) in Spain. The study material consisted of 3,586 mandibles from 2,548 red deer and 1,038 fallow deer shot during sport hunting, herd management culls, and programs for population control between 1988 and 1997 (period 1) and 2002 and 2009 (period 2) in eastern Sierra Morena, southern Spain. Disease prevalence ranged from 0.36% to 10.91% among age groups. Older animals were significantly more likely to be affected than younger ones. Red deer stags had higher prevalence than other groups. There was a significantly higher prevalence in period 1, probably associated with differences in climatic and population conditions. High population densities of female red deer contributed significantly to occurrence of disease. Intensive herd management and poor environmental conditions were considered risk factors that increased susceptibility to disease. The study of this affliction could be useful for monitoring general herd welfare and ecologic changes in Mediterranean ecosystems.
Our objective was to obtain images of a predictable level of quality using an intraoral X-ray system with digital imaging, avoiding patient overexposure. A polymethylmethacrylate (PMMA) physical test phantom was imaged at different exposure times and at various PMMA thicknesses using a dental imaging coupled charge device. Two identical regions of interest (ROIs) were chosen in every image file, and quality was numerically evaluated by measuring high-contrast spatial resolutions, low-contrast thresholds and signal-to-noise ratios. In addition, three practitioners proposed personal quality scores by image inspection. Numerical contents in the ROIs, related to the image quality, were plotted against exposure time. From here, a simple expression linking the exposure time with the thickness to obtain images of comparable quality was deduced. As a result, the optimum exposure time for imaging with a predictable level of quality can be inferred. The potential effect could imply savings above 1000 man Sv, roughly 20 % of the collective dose due to dental imaging, over a population of 1540 millions.
The efficiency of combined interblock-intrablock and intrablock analysis for the estimation of treatment contrasts in alpha designs is compared using Monte-Carlo simulation. The combined estimator considers treatments and replications as fixed effects and blocks as random effects, whereas the intrablock estimator considers treatments, replications, and blocks as fixed effects. The variances of the estimators are used as the criterion for comparison. The combined estimator yields more accurate estimates than the intrablock estimator when the ratio of the block to the error variance is small, especially for designs with the fewest degrees of freedom. The accuracy of both estimators is similar when the ratio of variances is large. The variance of the combined estimator is very close to that of the best linear unbiased estimator except for designs with small number of replicates and families or provenances. Approximations commonly used for the variance of the combined estimator when variances of the random effects are unknown are studied. The downward or negative bias in the estimates of the variance given by the standard approximation used in statistical packages is largest under the conditions in which the combined estimator is more efficient than the intrablock estimator. Estimates of the relative efficiency of combined estimators have an upward bias that can exceed 10% of the true value in small- and middle-sized designs with two or three replicates. In designs with four or more replicates, often used in forest genetics, the bias is negligible.
Detecting density‐dependence (DD) in population fluctuations is essential for population control, herd management and harvest programs. However, little information has been obtained for deer in Mediterranean ecosystems. We assess the effects of density, climate and harvesting on population growth fluctuations of two sympatric red (Cervus elaphus hispanicus) and fallow deer (Dama dama), in two hunting reserves located in a protected area of south‐east Spain. We use time series analysis of 16 consecutive years of abundance estimates and hunting extractions. We hypothesized a negative influence of density, deer hunting and drought on population growth rates. Through an integrative Bayesian state‐space modeling making possible a unified population analysis we have been able to not only estimate the effects of DD, climate and harvest extractions but also to evaluate their relative impacts on deer population in each location. We found deer populations exhibiting a very strong potential to grow from low density. We detected DD having a stronger effect than hunting and climatic factors, especially for overabundant deer populations close to their carrying capacity. Density‐dependent mechanisms compensate harvest extractions, reducing hunting effectiveness. Severe summer drought conditions had negative effects on growth rates and eventually led to delayed autumn deer deaths. The weather effect is more important the more abundant the deer are. In a climate change context, in Mediterranean environments the importance of weather factors could become much greater if both ungulates’ densities and aridity increase. Population size control here could modulate the negative effects of climatic constraints on deer and ecosystems conservation.
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